Pigmented metal powder



United States Patent 3,276,893 PIGMENTED METAL POWDER Joseph F. Quaas, Island Park, and John P. Broderick, Bayside, N.Y., assignors to Eutectic Welding Alloys Corporation, Flushing, N.Y., a corporation of New York No Drawing. Filed July 31, 1963, Ser. No. 299,090 6 Claims. (Cl. 106-290) This invention relates to a colored metal powder for flame spraying upon metal surfaces, and it more particularly relates to a blue powder.

Protective and decorative coatings are applied to metal surfaces by flame spraying finely divided metal powders upon them. It is advantageous to color these powders to identify them, and it is also advantageous'to incorporate fluxes in the powders for improving their wetting action.

In accordance with this invention, the mineral pigment lazurite or lapis lazuli is used to color a finely divided mesh metal powder. Such a pigmented powder incorporating minute amounts of from as low as 0.1 to 1.0% by weight of lazurite has remarkably effective wetting ability and self-fluxing action when flame sprayed, and is also readily identified by virtue of its azure blue color. The exact reason for the aforementioned phemenona is not completely understood, but it is believed that its lowering of surface tension might be attributable to the incorporation of some sodium sulfide in the lapis lazuli. The silicates in the lazurite probably promote fluxing and protection in the form of a slag during and after deposition. Its inorganic nature and high melting temperature prevent it from decomposing at normal flame spraying temperatures.

The mineral lazurite or lapis lazuli has been used since ancient times for jewelry and other ornamental purposes. Ground to powder it forms the pigment ultramarine, now, however largely superseded by artificial preparations. Lapis lazuli is a mixture of minerals, lazurite being the chief component. This mineral is isometric, and chemically a sodium, calcium, aluminum, sulfochlorosilicate. Lapis lazuli has a hardness of -5.5; specific gravity, 2.4; color, various shades of blue; luster, vitreous to greasy; translucent to opaque. Localities are Afghanistan, Siberia, Chile, Italy and California.

In applying this pigment to metal powders the natural occurring stone is pulverized to sub-micron fineness and suspended in a liquid vehicle, such as water, to act as an inorganic pigment. Its chemistry may also be described as follows:

3 mol-s of sodium aluminum silicate;

1 mol of sodium sulfide.

Powder which can be pigmented with lapis lazuli or lazurite with beneficial effects refluxing are those alloy systems covered by the B-Ni-Cr. classifications listed in the Brazing Manual (page 32), published by the American Welding Society, copyright 1955. The particle sized distribution encompasses material finer than mesh or down but held on a 325 mesh screen. That is, passing through a 150 mesh screen but retained on a 325 mesh screen.

Other alloy systems to be treated in like fashion are those consisting of Ni-B, Ni-ScB, Ni-Si and Ni-P, and the Stellite alloy systems including cobalt-chromium and tungsten and also nickel-cobalt base alloy ssytems.

What is claimed is:

1. A pigmented metal alloy powder consisting essentially of a finely divided metal alloy powder of approxi mately from 150v to 325 mesh particle size and an amount sufiicient to color said metal alloy powder of a coating of lazurite.

2. A pigmented metal alloy powder as set forth in claim 1 wherein said lazurite is incorporated in finely divided lapis lazuli.

3. A pigmented metal alloy powder as set forth in claim 1 wherein said lazurite comprises from 0.1% to 1.0% by weight of said powder.

4. A pigmented metal alloy powder as set forth in claim 1 wherein said powder is selected from the group consisting of nickel, cobalt and chromium alloys.

5. A pigmented metal alloy powder as set forth in claim 1 wherein said powder is a nickel alloy.

6. A pigmented metal alloy powder as set forth in claim 5 wherein said lazurite comprises approximately from 0.1% to 1.0% by weight of said powder.

References Cited by the Examiner UNITED STATES PATENTS 3,111,497 11/1963 Haas 106290 TOBIAS E. LEVOW, Primary Examiner.

I. POER, Assistant Examiner. 

1. PIGMENTED METAL ALLOY POWDER CONSISTING ESSENTIALLY OF A FINELY DIVIDED METAL ALLOY POWDER OF APPROXIMATELY FROM 150 TO 325 MESH PARTICLE SIZE AND AN AMOUNT SUFFICIENT TO COLOR SAID METAL ALLOY POWDER OF A COATING OF LAZURITE. 